Make your own - several people have put recipes here already. It's great for kids to see that they don't need processed or ready-made foods, that they have the ingredients here in the house. In fact, you can start them helping you in the kitchen with real pizza, real garlic butter, etc.
Do they like the fried zucchini you can get a pizza places? I saw a great recipe and it's a delicious and healthy snack by itself or with pizza. Cut zucchini spears or disks (I think the disks are easiest.) Pour some olive oil (light or EVOO) in the well of a plate. Mix up a combination of Parmesan cheese (I use the real shredded stuff, not the powdered stuff in the jar) and panko bread crumbs (you can use whole wheat or regular bread crumbs). If you want to add ground pepper, do so. The Parm cheese is pretty salty so you don't need to add that. Dip the zucchini disks in oil, both sides, then dip in the cheese/crumb mixture, then put on a baking sheet. If you have extra crumbs, sprinkle on the top of the zucchini once they are in place on the sheet. Bake at 375 or whatever temp you are using for the pizza, until slightly browned - usually about 10 minutes depending on what else is in the oven. They are crispy and better than the deep-fried version - also much cheaper. You could also do this with yellow squash, couza squash, and similar varieties. It's a great use for "day-old" zucchini if you don't want to make a zucchini bread or anything else elaborate.